1. Field of the Invention
The present invention relates to a method and a construction of electric connection to an oxide superconductor, and more specifically to an electrical connection to an oxide superconductor which can be effectively implemented in a superconductor device using an oxide superconductor thin film.
2. Description of Related Art
Superconductor devices using an oxide superconductor thin film have been expected to be an oxide superconductor product which will be reduced to practice first. In general, most of this type superconductor devices use the oxide superconductor in the form of a thin film. In this case, an oxide superconductor portion of the superconductor device has to be connected to an internal or external normal conductor. However, a connection technique for this purpose has not yet been established. Some of researchers have tried to squeeze a drop of indium (In) onto a surface of the oxide superconductor so as to bring the drop of indium into electric contact to the oxide superconductor, and then, to connect a leading wire through the drop of indium to the oxide superconductor.
When the oxide superconductor thin film is exposed to the atmosphere, a surface of the superconductor thin film is deteriorated due to moisture contained in the atmosphere and other factors. More specifically, if the oxide superconductor is left in the atmosphere, a very thin insulating layer will be formed on a surface of the oxide superconductor in contact with the atmosphere. Therefore, if a connection wire is led directly from the surface of the oxide superconductor, an ohmic contact having a sufficiently low resistance cannot be obtained due to a contact resistance through the very thin insulating layer on the oxide superconductor. As the result, a characteristics of the superconductor device cannot be fully utilized.